1. Technical Field
The present invention relates to a method for processing a substrate and a method of fabricating an apparatus including the processed substrate, and chemical solution to be used in the method.
2. Description of Related Art
A wiring in a circuit has been conventionally formed, for instance, by forming an organic film pattern on a semiconductor wafer, a liquid crystal display (LCD) substrate or other substrates, and etching a film underlying the organic film pattern, that is, the substrate with the organic film pattern being used as a mask to thereby pattern the underlying film. After the underlying film has been patterned, the organic film pattern is removed.
For instance, Japanese Patent Application Publications Nos. 2002-202619, 2002-334830, 2005-159292, 2005-159342, and 2005-159293 have suggested a method of processing an organic film pattern, including processing an underlying film, deforming an organic film pattern, etching the underlying film with the deformed organic film pattern being used as a mask, and removing the organic film pattern.
Specifically, the suggested method includes a step of deforming an organic film pattern (hereinafter, referred to as “fusion/deformation step”, or referred to as “gas-atmosphere applying step” because the “fusion/deformation step” is carried out by exposing a substrate to gas atmosphere), patterning an underlying film with the deformed organic film pattern being used as a mask, and removing the organic film pattern.
Namely, the suggested method includes the fusion/deformation step (specifically, the gas-atmosphere applying step) as a principal step.
In order to stably carry out those steps, the method may include steps of controlling (specifically, lowering) a temperature of a substrate to a suitable temperature, and heating the organic film pattern to be able to readily bake the organic film pattern after the organic film pattern has been deformed. The step of heating the organic film pattern may be carried out by broadening a range of a temperature in which the step of controlling a temperature of a substrate is carried out.
FIGS. 11A, 11B and 11C show steps to be carried out in the above-mentioned related method.
As illustrated in FIG. 11A, the first related method of processing a substrate includes in sequence of a substrate-temperature controlling step S102 of controlling a temperature of a substrate, a gas-atmosphere applying step S103 of applying gas atmosphere to the substrate, a heating step S104 of heating the substrate, and a substrate-temperature controlling step of S1021 of controlling a temperature of the substrate.
As illustrated in FIG. 11B, the second related method of processing a substrate includes in sequence of a first removal step J1, a substrate-temperature controlling step S102 of controlling a temperature of a substrate, a gas-atmosphere applying step S103 of applying gas atmosphere to the substrate, a heating step S104 of heating the substrate, and a substrate-temperature controlling step of S1021 of controlling a temperature of the substrate.
As illustrated in FIG. 11C, the third related method of processing a substrate includes in sequence of a first removal step J1, a second removal step J2, a substrate-temperature controlling step S102 of controlling a temperature of a substrate, a gas-atmosphere applying step S103 of applying gas atmosphere to the substrate, a heating step S104 of heating the substrate, and a substrate-temperature controlling step of S1021 of controlling a temperature of the substrate.
The steps illustrated in each of FIGS. 11A, 11B and 11C define a process of patterning an organic film formed on a substrate.
The first removal step J1 shown in FIGS. 11B and 11C may be comprised of a first chemical-solution step S1, an ashing step S7, or a combination of an ashing step S7 and a first chemical-solution step S1 (these steps are explained later in detail with reference to FIG. 2).
The second removal step J2 shown in FIG. 11C may be comprised of a second chemical-solution step S5, an ashing step S7, or a combination of an ashing step S7 and a second chemical-solution step S5 (these steps are explained later in detail with reference to FIG. 3).
Each of the first removal step J1 and the second removal step J2 is carried out in order to remove an alterated layer or a deposited layer both formed on an organic film pattern, to selectively remove only an alterated layer or a deposited layer, or to remove an alterated layer or a deposited layer to thereby cause a non-alterated portion of an organic film pattern to appear.
The substrate-temperature controlling step S102 of controlling a temperature of a substrate may be omitted.
The gas-atmosphere applying step S103 of applying gas atmosphere to a substrate, in the methods shown in FIGS. 11A, 11B and 11C, acts as a fusion/deformation step, namely, has a function of fusing and thereby deforming an organic film pattern.
In the gas-atmosphere applying step S103, an organic film pattern is exposed to gas atmosphere obtained by vaporizing an organic solvent such as alcohol (R—OH), alkoxyalcohol, ether (R—O—R, Ar—O—R, Ar—O—Ar), ester, ketone, glycol, alkylene glycol, and glycol ether (R indicates an alkyl group or a substituted alkyl group, Ar indicates a phenyl group or an aromatic ring other than a phenyl group), and thus, the organic solvent penetrates the organic film pattern. As a result, the organic film pattern is fused, and thus, liquidized or fluidized (hereinafter, referred to as “chemical-solution fusion reflow”). Thus, the organic film pattern is deformed.
The chemical-solution fusion reflow step causes an organic film pattern to deform in the range of 5 to 20 micrometers. It is sometimes possible to deform an organic film pattern by 100 micrometers or more.
However, since an organic film pattern is much deformed, if the organic film pattern is required to be accurately patterned, it would be necessary to accurately control the deformation of the organic film pattern.
In order to reduce a number of photolithography steps, there may be used an organic film pattern (specifically, a resist pattern) for forming a source and a drain in a channel. The fusion/deformation step is used for deforming two separate portions of the resist pattern located in the vicinity of a channel, corresponding to the source and drain, thereby unifying the separate two portions to each other.
It is necessary to cause much “chemical-solution fusion reflow” in order to stably unify the separate two portions to each other. However, if “chemical-solution fusion reflow” is carried out so much, a resist pattern associated with portions other than a channel, such as wirings, would be much fused and deformed.
Accordingly, it was necessary to design a resist pattern to have two portions having different thicknesses from each other, and to remove a thinner portion of the resist pattern before carrying out the fusion/deformation step.
However, since an organic film pattern would have an increased area due to the fusion/deformation step, it would be necessary to accurately control a time for carrying out the fusion/deformation step to thereby control accurately the deformation of an organic film pattern, in order to prevent an area of the organic film pattern from increasing.
Though there is a need for a process which is capable of reducing costs and saving energies and resources, there were not suggested an effective apparatus and method for doing so.